The presence of airborne particles such as pollen, fungal spores and dust mites in bedrooms is associated with respiratory diseases such as asthma. The United States National Institutes of Health (NIH) recommends removing such things as pets, rugs, carpets and curtains to reduce the presence of allergens in the bedroom (NIEHS Fact Sheet #9, ASTHMA, 7/97). A known solution is to place an air filter in the bedroom such as the Austin Healthmate which includes HEPA (High Efficiency Particulate Arresting) filters and activated carbon. HEPA technology is described in U.S. Pat. Nos. 4,629,482, 4,685,944 and 6,289,974. Such air filters are provided as free-standing units as shown in FIG. 1. These devices are said to clean the air in a typical sized bedroom in 15 to 30 minutes. Known problems with such devices include that they can be too noisy to run continuously while a person is attempting to sleep in the same room, as well as the possibility of the room becoming recontaminated every time that the door, windows or ventilation ducts are opened.
A known acute therapy for asthma is oral delivery of a broncho-dilator such as albuterol (also known as salbutamol). One form of this drug is Ventolin™ manufactured by SmithKline Beecham. Another example of a therapy used for the treatment of asthma is the delivery of a vasodilator such as a therapeutically effective amount of nitric oxide as disclosed in U.S. Pat. No. 5,873,359.